Abstract
Diffractive optical element (DOE)-type hologram memory is expected to large scale achieve read only memory (ROM). To duplicate the hologram ROM effectively, we used nanoimprint lithography. In this case, a master mold with multi steps is necessary . Previously, we have obtained hologram memory with eight steps using electron beam direct writing, and the obtained pattern made of an electron beam resist can use for the master mold directly. However, this electron beam resist layer is not sufficiently tough for repeated use in ultraviolet nanoimprint lithography. To improve this performance, we made a three-dimensional silicon mold from this master mold. The process employs liquid transfer imprint lithography to obtain a thin residual layer and succeeding dry etching. We thus obtained a three-dimensional silicon mold with eight steps; however, the surface was still rough.
